Fasting leptin and appetite responses induced by a 4-day 65%-energy-restricted diet

Objective:Animal studies show that the leptin decline after acute severe caloric restriction is a peripheral signal to increase food intake. However, most human studies have failed to observe such a relationship. We studied the acute effects of severe caloric restriction on the association between serum leptin concentrations and subjective appetite.Subjects:A total of 44 healthy adult men (aged: 43±5 years; BMI: 27.3±3.2 kg/m2).Measurements:Fasting serum leptin concentrations and self-perceived appetite levels were measured during a 4-day diet containing 36% of the estimated energy requirements. Appetite levels were assessed with a 10-point Likert scale, reflecting hunger, fullness, desire to eat, prospective consumption and total appetite.Results:After the 4-day energy deficit, fasting leptin concentrations decreased by 39.4% (95% CI: −43.6; −34.9%). This decline was associated with an increase in fasting hunger (r=−0.42; P<0.01), desire to eat (r=−0.39; P<0.05) and total appetite (r=−0.38; P<0.05). Furthermore, the association between fasting leptin concentrations and fasting appetite levels became stronger during the energy restriction period (for total appetite: day 0 r=−0.15, P=0.32; day 2 r=−0.31, P=<0.05; day 4 r=−0.41, P<0.01).Conclusions:The acute proportional reduction in fasting leptin after 4-day energy restriction is associated with an increase in self-perceived appetite. Additionally, the inverse association between proportional fasting leptin concentrations and self-perceived appetite response becomes stronger as energy restriction is prolonged. These findings suggest that leptin has an instrumental role in restoring energy balance in humans through the expression of appetite.